Answer:
q₁ = -2.92 nC
Explanation:
Given;
first point charge, q₁ = ?
second point charge, q₂ = 10 nC
net flux through the surface of the sphere, Φ = 800 N.m²/C
According to Gauss’s law, the flux through any closed surface (Gaussian surface), is equal to the net charge enclosed divided by the permittivity of free space.

where;
Φ is net flux
net charge enclosed
ε₀ is permittivity of free space.
= Φε₀
= 800 x 8.85 x 10⁻¹²
= 7.08 x 10⁻⁹ C
= 7.08 nC
q₁ + q₂ = 
q₁ =
- q₂
q₁ = 7.08nC - 10 nC
q₁ = -2.92 nC
The watts determine the brightness. Watt is the unit of Power. And Power is equal to Voltage x Amps (current). So both the current and voltage determine the brightness.
Answer: There is not work done at the door because the door did not move.
Explanation: Work is defined as the movement done by a force.
So if you move to apply a force F in an object and you move it a distance D, the work applied on the object is
W = F*D
In this case, the secret agent pushes against the door, so there is a force, but the agent does not move the door, so D = 0, so there is no motion of the door, which implies that there is no work done at the door.